The timing of a congressional vote remains to be determined. Lawmakers aren’t scheduled to return from their summer recess until September 9. Congressional leaders have not said whether they will call members back sooner. Indeed, they may be surprised that Obama asked for a vote. The letter House Speaker John Boehner sent the president this week asked for consultations on Syria; it didn’t demand a vote. (Congressional leaders also have fit Syria into a tight calendar. Congress is scheduled to be in session for just nine legislative days in September; most of those days were supposed to be spent trying to find a way to keep the government running once the new fiscal year starts on October 1.)

Will Congress give Obama the authority he is seeking? The odds are it will. Most Democrats are likely to stand by him, even if only out of party loyalty. Skeptical lawmakers on both sides of the aisle will also confront the argument that a “no” vote would gravely damage U.S. credibility in dealing with Iran, North Korea, and other potential threats.

Still, widespread doubts about the wisdom of a military strike against Syria make a “yes” vote far from certain—or easy to obtain. The memories of the bad intelligence on Iraq could prompt tough questions about the evidence the White House has today. White House officials will understandably be reluctant to discuss the details of its planned military operations. That might not satisfy members who fear that the administration will go too far or that it has no strategy for what to do if Syria persists in using chemical weapons. And writing authorizing legislation that satisfies the administration while being sufficiently limited to assure lawmakers that they aren’t giving the White House a blank check they might later regret—as happened with the Gulf of Tonkin Resolution and the Iraq War authorization—could prove difficult.

However the Syria vote goes, it sets a precedent. Any future effort to initiate the use of military force will come with heightened public expectations that the president, whether Obama or his successors, will first go to Congress. But it hardly guarantees they will. Syria lacks many of the attributes that presidents and their lawyers have traditionally cited when justifying unilateral presidential military action: it is not an act of self-defense; it is not pursuant to a UN Security Council authorization (as Obama argued in Libya) or a regional organization (as Bill Clinton claimed with NATO in Kosovo); it does not involve protecting American lives or property (as Ronald Reagan claimed in Grenada and George H.W. Bush argued in Panama); and time is not of the essence. Given different circumstances, future administrations might dispute the premise that presidents have to look to Capitol Hill before ordering the military into combat.

Finally, if the White House is hoping a vote on Syria will protect Obama politically in the event a military attack goes wrong, it should prepare to be disappointed. A vote for war has never stopped members of Congress (or the American public) from turning on a president when things go badly. Just ask George W. Bush.

Opinions expressed on CFR blogs are solely those of the author or commenter, not of CFR, which takes no institutional positions.